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Magnetic sensor

a technology of magnetic sensor and connecting portion, applied in the field of magnetic sensor, can solve problems such as different load applied to the control system, and achieve the effects of good detection property, and reducing the resistance of the connecting portion and the relative variation

Active Publication Date: 2011-02-03
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a magnetic sensor that is smaller and lighter than previous versions, while still maintaining its detection properties. The sensor includes a bridge circuit with magneto-resistive elements arranged on a substrate. The first and second magneto-resistive elements are connected through a first connecting portion in the central region of the sensor. The third and fourth magneto-resistive elements are connected through a second connecting portion that crosses the first connecting portion with a distance. The resistance values of the magneto-resistive elements change in the same direction when a voltage is applied, and the resistance values of the second and fourth magneto-resistive elements change in the opposite direction when a voltage is applied. The sensor also includes an angle calculating circuit and a potential difference detecting section. Overall, the sensor provides a more compact and reliable solution for detecting magnetic fields.

Problems solved by technology

However, in this case, a load different from that of a control system is applied and any adverse affect may occur to the control system.

Method used

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first embodiment

[0041]Firstly, the configuration of a magnetic sensor as a first embodiment of the invention will be described with reference to FIG. 1 to FIG. 3. FIG. 1 is a schematic view showing the entire configuration of the magnetic sensor of this embodiment, FIG. 2 is a circuit diagram showing the circuit configuration in the magnetic sensor, and FIG. 3 is a plane view showing a detailed configuration of key components in the magnetic sensor.

[0042]As shown in FIG. 1, the magnetic sensor has first to eighth magneto-resistive (MR) elements 1 to 8, terminals T1 to T8, connecting portions L1 to L8 (partly omitted in FIG. 1), difference detectors AMP1 and AMP2, and an angle calculating circuit 50 (omitted in FIG. 1) on a substrate 10. The first to eighth MR elements 1 to 8 are evenly arranged so as to surround a central region R1 and make a circle in a peripheral region. Among the MR elements, the first to fourth MR elements 1 to 4 form a first bridge circuit 11 (FIG. 2), and the fifth to eighth ...

second embodiment

[0086]The configuration of a magnetic sensor as a second embodiment of the invention will be described with reference to FIG. 6 to FIG. 8. FIG. 6 is a schematic view showing the entire configuration of the magnetic sensor of this embodiment, FIG. 7 is a circuit diagram showing the circuit configuration of the magnetic sensor, and FIG. 8 is a plane view showing a detailed configuration of key components in the magnetic sensor.

[0087]The magnetic sensor of this embodiment has two half-bridge circuits including a pair of MR elements that are connected in series between a power source and the ground. For other points, the magnetic sensor of this embodiment has a substantially same configuration as the magnetic sensor of the first embodiment. Note that, in this embodiment, the components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

[0088]As shown in FIG. 6, the magneti...

third embodiment

[0093]Now, a configuration of a magnetic sensor according to a third embodiment of the invention will be described with reference to FIGS. 9 to 11. FIG. 9 schematically illustrates the entire configuration of the magnetic sensor according to the third embodiment. FIG. 10 illustrates a circuit configuration of the magnetic sensor illustrated in FIG. 9. FIG. 11 is a plane view illustrating a key configuration of the magnetic sensor illustrated in FIG. 10 in detail.

[0094]In the first and the second embodiments, two full-bridge circuits (the first bridge circuit 11 and the second bridge circuit 12) or two half-bridge circuits (the first half-bridge circuit 13 and the second half-bridge circuit 14) are used to obtain the rotational angle θ of the signal magnetic field Hm over all directions (from zero degrees to 360 degrees both inclusive). However, the magnetic sensor according to the third embodiment illustrated in FIGS. 9 to 11 may be used when the rotational angle θ is limited to a r...

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PUM

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Abstract

A magnetic sensor includes first to fourth MR elements. The first and second MR elements are connected at respective ends thereof through a first connecting portion in a central region. The third and fourth MR elements are connected at respective ends thereof through a second connecting portion that crosses the first connecting portion with a distance in a thickness direction in the central region. The first and fourth MR elements are connected at respective other ends thereof through a third connecting portion, and the second and third MR elements are connected at respective other ends thereof through a fourth connecting portion. Resistance values of the first and third MR elements change in a same increasing / decreasing direction, whereas resistance values of the second and fourth MR elements change in an increasing / decreasing direction opposite to the first and third MR elements, depending on an external signal magnetic field.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a magnetic sensor capable of detecting a change in a magnetic field with high sensitivity.[0003]2. Description of the Related Art[0004]Generally, to accurately detect a weak control current flowing through a circuit in a control apparatus, a method of connecting resisters in series in the circuit and measuring a voltage drop of the resisters is used. However, in this case, a load different from that of a control system is applied and any adverse affect may occur to the control system. Accordingly, a method of indirectly measuring a control current by detecting the gradient of the induction magnetic field generated by the control current has been used. In particular, a magnetic sensor in which giant magneto-resistive elements (hereinafter, GMR element) expressing giant magneto-resistive effect are arranged in the induction magnetic field by the control current to detect the gradient has been prop...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G01R33/02
CPCG01R33/091G01D5/145
Inventor YAMAZAKI, HIROSHIHIRABAYASHI, HIRAKUOHTA, NAOKI
Owner TDK CORPARATION